This invention relates to a multi-component elongated shaft, especially suited for golf clubs. More particularly, this invention relates to a shaft for a golf club having a metal portion adjacent the club end and a composite portion, made from a material such as graphite or boron/graphite fibers, at the grip end. Still more particularly, this invention relates to such a golf club shaft and a method of making the same wherein a composite grip end portion is joined to and merges with a metallic club end portion.
A golf club shaft is provided with a number of characteristics of length, weight, balance, diameter, and taper to impart an appropriate "feel" to its user, and to mechanically transfer power and speed during its stroke to the golf ball. Historically, such shafts have been made from a number of different types of materials. For example, wooden shafts were originally quite popular but were eventually replaced with lightweight hollow metallic shafts. Later, composite materials such as fiber reinforced plastic replaced metallic shafts for weight reduction.
Shafts having multiple components are known to the art, such as are discussed in U.S. Pat. No. 4,725,060, for example. Such clubs include reinforcing filaments such as carbon filaments nown filament winding method.
The use of a graphite filament tubular shaft is known from U.S. Pat. No. 3,873,090. There, a steel hosel and a graphite filament shaft 12 are joined by an elongated pin inserted into a bore in the shaft and a suitable bonding agent. Similarly, in U.S. Pat. No. 4,555,113, a shaft body is prepared by rolling an inorganic fiber sheet made of fiberglass carbon cloth, boron fiber cloth, or a combination thereof into a multi-layered cylindrical body which is adhered to a plastic resin layer.
However, it has remained a problem in the art to continue to produce the correct "feel" for the golf club while utilizing graphite or boron/graphite materials. Thus, it is desired to preserve the center of gravity of the club nearer to the club face while obtaining the advantages of the use of lighter weight materials.
Accordingly, it is an overall object of this invention to prepare a shaft especially suited for use with a golf club which comprises a metal portion joined with a composite material portion at a location spaced along the length of the shaft.
It is an additional object of this invention to provide a shaft having a metal portion at the club end of a golf shaft adjoining a graphite portion at the grip end of the shaft.
It is still another object of this invention to provide a golf shaft with a hollow tubular metallic portion adjoining a fiber composite portion so that the center of gravity of the shaft lies nearer to the club end than to the grip end.
These and other objects of the invention will become apparent from a detailed description of the invention which follows taken in conjunction with the accompanying drawings.